In the navigation of a vehicle over a prescribed route contour maps are commonly used to provide an indication of the terrain over which the vehicle is traveling. The information afforded by contour maps, assorted vehicle instrumentation, and visual observation enables the operator to navigate the vehicle as it travels along its prescribed route. Thus, a pilot navigating an aircraft, for instance, uses contour maps, instrumentation readings and visual observation in order to determine altitude and other course parameters have traditionally defined a navigational instrument used primarily to aid in the navigation of the vehicle along a pre-defined path.
U.S. Pat. No. 4,682,160 issued to Beckwith Jr. et al. on Jul. 21, 1987, describes a system which generates a real time perspective view of the terrain lying along an aircraft's flight path for the benefit of the pilot of an aircraft employing the system. The system of the Beckwith, Jr. et al. patent accesses terrain data stored as digital information in a digital map generator and then converts the digital data into the perspective representation of the terrain which may be viewed on an appropriate input/output device, such as a cockpit CRT (cathode ray tube) instrument panel. The real time perspective representation provided to the pilot of the aircraft approximates the view the pilot would have if actually looking out a window of the aircraft during high visibility conditions.
The Beckwith et al. patent defines a hardware device that accesses terrain data which is converted into a perspective representation of the terrain which is displayed on a display device, such as a CRT instrument panel, for the pilot to see. The contour representation of the terrain on the display device represents a perspective as if the pilot were actually viewing the terrain himself during high visibility conditions. The Beckwith et al. patent offers the advantage of allowing a pilot to fly during inclement weather conditions with the aid of a display which provides terrain information of the type that would be available to the pilot's naked eye during high visibility weather conditions.
The hardware implementation of the Beckwith et al. patent produces a wire-frame model of the terrain over which the aircraft is flying. The Beckwith et al. patent requires a great number of contour paths in order to generate a wire-frame model of the terrain is a limitation. Additionally, the hardware approach of the Beckwith et al. patent does not provide as flexible a solution as could be achieved with a software approach.
U.S. Pat. No. 5,488,563 issued to Chazelle et al. on Jan. 30, 1996 defines a device that correlates the terrain data with the flight path of an aircraft to define an anti-collision mechanism and warning system. Memory of the device stores terrain information of a very large area of the earth. As a function of the position of the aircraft, the appropriate local map is temporarily transferred into a fast access memory of the device and an altitude envelope of the aircraft is developed given local terrain information, velocity and acceleration vectors for the zone in which the aircraft is flying. The device further has anti-collision processing capabilities such that an alarm indicates if the flight path of the aircraft violates a predetermined relation between a protection field and the altitude envelope. The Chazelle et al. patent uses either an inertial navigational unit or a radio navigational instrument to generate a synthetic image representative of a flight path trajectory that will avoid collision with the terrain over which the airplane is flying. The synthetic image representative of a flight path trajectory is not a 3-D image of the terrain over which the airplane is flying.
The flight management technology of the Chazelle et al. patent studies terrain curves in order to calculate an exit path for the airplane. The positional information required in order to calculate the exit path necessarily includes flight information parameters that must be supplied by the flight management system of the aircraft. This is clearly shown by Informations in flight block 2 of FIG. 2 of the Chazelle et al. patent. Such flight parameters would include information with regard to the inertial unit 20, radio navigational instrument 21, and Radio-altimeter 22 all shown in FIG. 3. The inertial unit 20 provides information on the velocity and acceleration of the aircraft from which the angle of incidence, yaw, slope, pitch, heading, and bank may be determined. The angular values are used in the vicinity of the acceptable flight deck of the aircraft.
There is currently an unmet need in the art to be able to provide a navigator of a vehicle with terrain information over which the vehicle is traveling regardless of weather and visibility conditions in a manner that is not dependent upon trip information such as velocity and acceleration of the vehicle and in a manner that is more flexible than the hardware solution to be found in the prior art. There is a need in the art for the terrain information to be a 3-D, non-wire frame image different from the synthetic image representative of an exit path generated by the invention of the Chazelle et al. patent. Additionally, there is an unmet need in the art to provide such terrain information to navigators of a variety of vehicle types including, but not limited to, aircraft.